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Crosshead.                                   245

slant edge, and a liner to represent adjustment allowance, and
the whole chucked in the lathe, as at / Two settings are of
course necessary. (See Appendix /., p. 752.)

The "Wedge is now shaped to dimension, but not drilled;
the wedge bolt and set screw for the large end both prepared.
The oil-cup cover is then turned and screwed in a concentric
chuck, and milled on the hexagonal faces with a horizontal tool
by placing the work on a dividing plate. All is now ready to put
together. For the small end, fit the brasses in place by smooth
filing and scraping; fit the wedge, and mark off the hole for bolt
by scribing through the rod end. Remove wedge for drilling and
tapping, then replace. For the large end, the gib and cotter are
first carefully fitted to their holes separately; then the brasses are
fitted to the strap, and the latter to the butt end. Place all
together, and file the cotter till it enters the proper amount; then
mark off the split-pin hole and drill. Once more replace all
parts, and the connecting rod is complete.

XXII. Crosshead (Fig. 254).—Centre the forging, as at
B, and line the width across the cheeks; then turn the side and
end, and shape the flats. Lay now upon the marking table, as at
c (see both views), and scribe the horizontal centre line. Find
the centre for the gudgeon hole, as at a and £, measuring from a
straight edge, and test also with dividers; erect this line with
square, and strike the circle on both sides, also the contour of the
boss. Chuck in the lathe, as at L, and bore the hole, first
drilling to admit the boring tool. Remove from the dogs, and
insert next in a large bell-chuck, as at D, the exact position
being found by placing the work between the lathe centres; after-
wards firmly tightening up the screws, as shewn. First drill the
hole as large as allowable, the tool being centred, as at F, and
clamped in the slide rest; and next bore the taper, as at E, by
turning the top slide of the rest to the required angle, the feed
being obtained by a small pulley on the screw, driven from the
countershaft by catgut band. The hole is tested for diameter with
callipers, and the angle of the rest noticed before removing (this
being afterwards required for the Piston Rod). Now place the
crosshead on the mandrel of a shaping machine, as at G, and sbape
all round up to the return curve, the latter being tooled with a